Laser printers have become widely used in medical imaging to produce hard copy (film) images of electronic medical images derived from a variety of sources (e.g., medical film digitizers, computed and direct radiography, diagnostic imaging modalities--CT, MRI, PET, US). Typically, electronic medical images are processed before printing for various image characteristics, such as contrast, window, level, reverse image, density. A change in contrast changes the code value to density mapping. In existing wet process laser printers, contrast was included in an output look-up-table, taking advantage of the inherent nonlinearity of the printer's code value to density relationship to provide roll-off at low and high densities for contrast greater than 0.
With the advent of dry laser printers, it is desirable to provide greater control over contrast which is greater than zero.